Internal dry powder delivery system and method thereof

ABSTRACT

An internal dry powder delivery system through a working channel of an endoscopic cannula for directly applying the powder form medication to an internal tissue/organ site, includes an elongated tubular delivery channel and a powder supply device for producing pressurized gas mixing with the dry powder for feeding to form a mixture of dry powder and pressurized gas delivering to an internal tissue/organ site through the delivery channel via endoscopic cannula. It ensures a smooth powder release by preventing liquid from accumulation at the tip of the delivery channel and offers physicians a new powder form drug delivery method via endoscope. Also, it offers new minimal invasive application by directly and precisely applying the powder format drug to the internal sites of human gastrointestinal organ via endoscope to achieve hemostasis, anti-inflammation, anti-ulcer and anti-tumor treatment, etc.

CROSS REFERENCE OF RELATED APPLICATION

This is a Divisional application that claims the benefit of priorityunder 35 U.S.C. §119 to a non-provisional application Ser. No.13/658,798, filed Oct. 23, 2012, which is a Continuation application ofa non-provisional application, application Ser. No. 12/932,582, filedFeb. 28, 2011, which is a Continuation-In-Part application of anon-provisional application, application Ser. No. 12/657,224, filed Jan.15, 2010.

BACKGROUND OF THE PRESENT INVENTION

Field of Invention

The present invention relates to dry powder delivery system, and moreparticular to an internal dry powder delivery system and method thereoffor delivering dry powder to reach internal operation site, especiallyduring a minimally invasive surgery or other similar internalapplication for beings such as humans or animals.

Description of Related Arts

Generally, medications are in liquid form, capsule form, pill form, andpowder form. The common difficulty for physicians is how to directlyapply powdered medication to the internal tissue/organ site of a humanor an animal such as human gastro-intestine.

Traditionally, the only application of powdered medications is toenclose the powder in a capsule made of a material that will notimmediately dissolve or to compress the powder into the pill form. Whenthe capsule or pill is consumed into the patient's stomach andintestine, the enclosure skin of the capsule will dissolve and thepowder particles will be exposed and absorbed.

Conventionally, powder form medications can be applied by topicalapplication during open surgery. It may normally be ingested as tabletsor powder capsules. Tablets and powder capsules' strengths are oftendiluted by gastric and intestinal juice and could not offer precisedelivery and dosage control to the target wound site. In turn,physicians can not accurately control the amount of medication reachingthe designated site. Therefore, it cannot be used when physicians wantto directly control the dosage and dryness status of the powder to applythe target wound sites of human gastro-intestine before contact withliquid in the digestive system.

The minimal invasive procedure via endoscope has been widely used fordiagnosis and surgery. When using endoscope during inspection andsurgery, physicians often need to apply medications to an internaltissue site. Via endoscope, physicians can inspect the internalorgan/tissue and conduct surgical procedures inside of the human body.In general, endoscopes consist of gastro-intestinal endoscope,laparoscope, thoracoscope, hysteroscope, cytoscope, laryngoscope, andnasopharyngoscope etc. Besides for medical use, endoscopes can also beused to inspect mechanical or electrical problems in the industries suchas automobile maintenance, mechanical setups, petroleum engineering,electrical facilities, aviator equipments, coal-gas passages,architectures, water pipe systems etc.

For example, laparoscope and gastro-intestinal endoscopes have astandard total length about 600 mm to 1700 mm depend on the applicationpurpose. Besides the imaging system, the internal components include anarrow working channel, similar to that of an irrigation channel or abiopsy clamp, allowing physicians to conduct minimally invasivesurgeries. Currently, the most common laparoscopic and gastro-intestinalscopes used by physicians for biopsy, have a diameter of 2.8 mm and 3.2mm respectively to enable physicians to insert catheters or devices toconduct examination, electrical incision, suture, applying medicationand hemostasis, etc.

Physicians often use laparoscope and gastro-intestinal endoscope duringtreatment and minimally invasive surgery to examine an internal site orto inject liquid medications. The long and narrow characteristics of theworking channel often cause occlusion when injection medications whichcould present certain limitations. In current clinical settings,endoscope's irrigation or working channel could only delivery liquidform medications (soluble/insoluble solutions and gel), restricting anypowder and particle form medications that could easily lose itseffectiveness when it contacts water prior to blood. In addition,through the use of endoscopes physicians could often examine gastritislesions including tumors or ulcers and thereby provide the appropriatetopical medication directly to the site. Due to the length and thenarrowness of most laparoscopes and endoscopes, particles often couldnot overcome the resistance presented between air pressure and the innerlining of the tube which could lead to tip occlusion. Also, gastro andintestinal juice/mucus could easily enter the working channel causingobstruction. The most common problems associated with delivering drypowder medication through the working channel of an endoscopic cannulainclude that dry powder particles often occlude because of resistance inthe long and narrow cannula through the working channel of endoscope andexcess liquid and pressurized air mixed with dry particles could causeocclusion at the tip of the delivery catheter. These common problemsminimize physicians' ability to deliver powdered medications directlyand precisely to the tissue/organ site of the human gastro-intestine viaendoscope.

Recently, natural orifice transluminal endoscopic surgery was developedfor minimally invasive surgical technique. The endoscope is insertedthrough natural orifices (such as mouth, anus and vagina) allowing forintra-abdominal diagnostic and therapeutic procedures without the needfor abdominal incisions. Moreover, the endoscope can also be insertedinto pre-existing orifices to access other body cavities (i.e. thoraciccavity and pelvic cavity). Hence a technique that utilizes the workingchannel of the endoscope as a vehicle to directly deliver medication tothe internal target tissue/organ has great clinical implications inmedicine.

The current invention specifically addresses these issues and providesphysicians a new alternative to delivery particles/powder formatmedications directly to an internal site of gastrointestinal tract andbody cavities via endoscope during minimally invasive surgeries for bothdiagnostic and therapeutic purposes.

SUMMARY OF THE PRESENT INVENTION

The present invention is advantageous in that it provides an internaldry powder delivery system which is capable of directly applying drypowder to internal tissue/organ site.

Another advantage of the present invention is to provide an internal drypowder delivery system via working channel of endoscopic cannula toovercome the difficulties when directly applying powdered medication tothe tissue/organ site of human gastro-intestine through the narrowworking channel of an endoscope.

Another advantage of the present invention is to provide a new drypowder-format drug delivery method and system thereof via workingchannel of endoscopic cannula, and its clinical applications, whichovercome the most common problems associated with delivering dry powdermedication through the working channel of an endoscopic cannula,including that dry powder particles often occlude because of resistancein the long and narrow cannula through the working channel of endoscopeand excess liquid and pressurized air mixed with dry particles couldcause occlusion at the tip of the delivery catheter, in which thesecommon problems minimize physicians' ability to deliver powderedmedications directly and precisely to the tissue/organ site of the humangastro-intestine via endoscope.

Another advantage of the present invention is to offer physicians aninnovative powder medication delivery system and method thereof, a newdiagnosis and treatment alternatives when performing a minimallyinvasive procedure, such as via endoscope.

Another advantage of the present invention is to offer physicians aninnovative powder medication delivery system and method thereof, a newdiagnosis and treatment alternatives when performing a minimallyinvasive procedure, such as via endoscope.

Another advantage of the present invention is to provide an innovativeinternal powder delivery system and method thereof which can directlyreach the internal tissues in the internal cavities and deliver internalpowder thereto.

Another advantage of the present invention is to offer physicians a newpowder medication delivery system through the working channel of theendoscope, to directly reach the internal tissues in thegastrointestinal tract, abdominal, chest and pelvic cavity and deliverbiomaterial for the purpose of tissue healing, sealing, anti-adhesion,fistula closure hemostasis etc.

Another advantage of the present invention is to provide a new powderform medication delivery method for physicians via endoscope. Thismethod could be used with various purposes such as hemostatic,anti-flammation, tissue repair, mucosal protection, ulcer repair andantineoplastic treatment, etc.

Another advantage of the present invention is to provide a dry powderdelivery system via the endoscope working channel that can be used todeliver biomaterials including nanomaterials, proteins, amino acids,minerals, trace elements, organic and non organic materials,polysaccharides, polymeric substances, fiber, microfiber, nutrientpowder, adhesives, and etc.

Another advantage of the present invention is to provide an internal drypowder delivery system which enables physicians to directly apply thebiocompatable polysaccharide hemostatic powder to the bleeding sites viaendoscope during minimally invasive surgery to achieve hemostasis.

In order to accomplish the above advantages, the present inventionprovides an internal dry powder delivery system for delivering drypowder from outside to an internal operation site, comprising:

an elongated tubular delivery channel having a feeding opening at oneend thereof, an emitting opening at a distal end thereof adapted forreaching a position adjacent to the internal operation site, a diameter3.2 mm or less, and a length long enough for enabling the emittingopening reaching the internal operation site; and

a powder supply device which is connected to the feeding opening of thedelivery channel and comprises:

a gas-powder chamber a dry powder inlet for feeding in a predeterminedamount of dry powder therein and a dry powder outlet communicating withthe feeding opening of the delivery channel; and

a pressurized gas feeder producing pressurized gas in the gas-powderchamber mixing with the dry powder therein to form a mixture of drypowder and pressurized gas for blowing into the delivery channel throughthe feeding opening thereof, thereby a continuous feeding of thepressurized gas and the mixture of dry powder and pressurized gas intothe delivery channel from the gas-powder chamber substantially rendersthe mixture of dry powder and pressurized gas to deliver to the emittingopening of the delivery channel and spray onto the designated internaloperation site.

The present invention also provides a method of delivering dry powderfrom outside to an internal operation site, comprising the steps of:

(a) extending a distal end of an elongated tubular delivery channel to aposition adjacent to an internal operation site while the other endthereof remains outside;

(b) producing pressurized gas and mixing the pressurized gas with drypowder to form a mixture of dry powder and pressurized gas in agas-powder chamber communicating with a feeding opening provided at theother end of the delivery channel; and

(c) continuously feeding the pressurized gas and the mixture of drypowder and pressurized gas from the gas-powder chamber into the deliverychannel via the feeding opening until a predetermined amount of themixture of dry powder and pressurized gas spray out of an emittingopening provided at the distal end of the delivery channel for applyingonto the internal operation site.

According to a preferred embodiment of the present invention, to preventfrom powder occlusion in the catheter while inserting catheter intoendoscope working channel to its designated position, a special featureof ‘dual gas channels’ was provided. One of the gas channels provides a‘maintaining gas flow’ to ensure that the pressure inside the catheteris higher than the pressure inside the gastrointestinal tract or thethoracic/abdominal cavity where the catheter tip is located. Thisprevents from gas reflux from the gastrointestinal tract orthoracic/abdominal cavity into the catheter which may result in powderocclusion in the catheter. The working gas flow on the other handdelivers the dry powder to the designated site through the catheter.

According to a preferred embodiment of the present invention, thedelivery channel can be inserted into a human or an animal body to reacha designated internal tissue operation site via a working channel ofendoscopic cannula.

Additional advantages and features of the invention will become apparentfrom the description which follows, and may be realized by means of theinstrumentalities and combinations particular point out in the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of an internal dry powder delivery systemaccording to a preferred embodiment of the present invention.

FIG. 2 is a sectional view of the internal dry powder delivery systemaccording to the above preferred embodiment of the present invention,wherein an alternative mode of the gas regulator is illustrated.

FIG. 3 is a sectional view of the internal dry powder delivery systemaccording to the above preferred embodiment of the present invention,wherein another alternative mode of the gas regulator is illustrated.

FIG. 4 is a sectional view of the internal dry powder delivery systemaccording to the above preferred embodiment of the present invention,wherein another alternative mode of the gas regulator is illustrated.

FIG. 5 is a sectional view of the internal dry powder delivery systemaccording to an alternative mode of the above preferred embodiment ofthe present invention

FIG. 6 is a sectional view of the internal powder delivery systemaccording to an alternative mode of the above preferred embodiment ofthe present invention.

FIG. 7 is a sectional view illustrating an end cap provided at theemitting opening of the delivery channel according to the abovepreferred embodiment of the present invention.

FIG. 8 is a schematic view of an internal powder delivery system, whichis embodied as a one way delivery system of hemostat powder duringsurgery, according to another alternative mode of the above preferredembodiment of the present invention.

FIG. 9 is a schematic view illustrating an alternative mode of theinternal powder delivery system in FIG. 8 according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 to 7, the present invention provides an internaldry powder delivery system and method thereof for delivering dry powderfrom outside to a designated internal operation site. According to apreferred embodiment, the present invention discloses a new dry powdermedication delivery method via endoscope, and its clinical applicationsthereof, as an example to illustrate the configuration and improvedfeatures of the present invention. It is preferably aimed to, but notlimited to, overcome the difficulties when directly applying powdermedication to the internal operation (tissue/organ) site of human oranimal such as human orgastro-intestine, organs, and etc. . . .

According to the preferred embodiment as illustrated in FIGS. 1-7, thepresent invention enables the delivering of dry powder medicationthrough a working channel of an endoscopic cannula. In order to do so,the following problems must be overcome:

(i) Dry powder particles often occlude because of resistance in the longand narrow cannula through the working channel of endoscope.

(ii) Excess liquid and pressurized air mixed with dry particles couldalso cause occlusion at the tip of the delivery catheter.

These common problems minimize physicians' ability to deliver powdermedications directly and precisely to the tissue/organ site of, forexample, the human gastro-intestine via endoscope. To effectivelyaddress the above technical difficulties, the present invention providesan internal dry powder delivery system for delivering dry powder fromoutside to an internal operation site, which comprises an elongatedtubular delivery channel 10 and a powder supply device 20.

The elongated tubular delivery channel 10 has a feeding opening 11 atone end thereof, an emitting opening 12 at a distal end thereof adaptedfor reaching a position adjacent to the internal operation site, adiameter preferably 3.2 mm or less, and a length long enough forenabling the emitting opening 12 reaching the internal operation site.

The powder supply device 20 which is connected to the feeding opening 11of the delivery channel 10 comprises a gas-powder chamber 21 and apressurized gas feeder 22.

The gas-powder chamber 21 has dry powder inlet 211 for feeding in apredetermined amount of dry powder therein and a dry powder outlet 212communicating with the feeding opening 11 of the delivery channel 10.

The pressurized gas feeder 22 produces pressurized gas in the gas-powderchamber 21 mixing with the dry powder therein to form a mixture of drypowder and pressurized gas for blowing into the delivery channel 10through the feeding opening 11 thereof. Thereby, a continuous feeding ofthe pressurized gas and the mixture of dry powder and pressurized gasinto the delivery channel 10 from the gas powder chamber 21substantially renders the mixture of dry powder and pressurized gas todeliver to the emitting opening 12 of the delivery channel 10 and sprayonto the designated internal operation site.

By means of the above system, the procedures of delivering dry powderfrom outside to the internal operation site comprise the steps of:

(a) extending a distal end of the elongated tubular delivery channel 10to a position adjacent to the internal operation site while the otherend thereof remains outside;

(b) producing pressurized gas and mixing the pressurized gas with thedry powder to form a mixture of dry powder and pressurized gas in thegas-powder chamber 21 communicating with the feeding opening 11 of thedelivery channel 10; and

(c) continuously feeding the pressurized gas and the mixture of drypowder and pressurized gas from the gas-powder chamber 21 into thedelivery channel 10 via the feeding opening 11 until a predeterminedamount of the mixture of dry powder and pressurized gas spray out of theemitting opening 12 of the delivery channel for applying onto theinternal operation site.

The gas mentioned above can be any, but preferable medical use cleanair, oxygen, or carbon dioxide, or the like. The pressurized gas feeder22 can be embodied as a manual air pump as shown in FIGS. 1 to 5. Theprocess begins when the air is pumped into the air-powder chamber 21(either by the manual pump as shown in FIGS. 1-5 or the electrical pumpas shown in FIG. 7) mixing with the dry particles of the dry powder.When the present invention is applied for diagnosis and treatment whenperforming a minimally invasive procedure via endoscope, the mixed drypowder and pressurized air are in turn delivered to an internal woundsite through the delivery channel 10 within the working channel of theendoscope. The dry powder finally is spray out to the target tissue orwound site from the emitting opening 12 of the delivery channel 10 underthe control and monitoring by physicians via endoscope.

The dry powder used in the present invention refers to dry, smooth andelastic particles. To also ensure a smooth delivery, powder particlesshould not exceed 400 um; the preferred particle diameter should bebetween 1 um-250 um. The dry powder used in the present invention canalso include nano particles and/or microfiber particles. To ensure asmooth delivery, the average size of the microfiber particles should notexceed 400 um and the preferred particle size should be between 0.01-200um.

The powder medications used in present invention include, but are notlimited to anti-inflammatory drugs (Amoxicillin, Norfloxacin, Gentamicinetc.), anti-ulcer drugs and agents (Omeprazole, Ranitidine,Metronidazole or mucosal protective agent etc.), and anti-neoplasticdrugs (Cytotoxic, hormones or biological response modifier). Accordingto the preferred embodiment of the present invention, powder formStarch-derived Absorbable Polysaccharide Hemostat, SAPH, is used as thedry powder for hemostasis at the internal wound site.

The dry powder used in the present invention also includes, but notlimited to, organic or non organic material, chemical substances andcompounds, minerals, lipids, polymer, polysaccharide, fiber, proteins,amino acids, polypeptide, and etc.

The dry powder used in the present invention such as nanomaterial andbiomaterial include, but not limited to, biocompatible hemostats,surgical adhesives, sealant, anti-adhesion material, enforcementmaterial, fistula closure material, wax, and etc.

Referring to FIGS. 1 to 4, the internal dry powder delivery system ofthe present invention offers physicians an alternative method to applydry hemostatic powder to an internal operation site which can be asurgical wound site.

The powder supply device 20 is embodied to comprise a pressurized gasfeeder 22 which is an elastic hollow air pump securely connected to abase 23 in a detachable manner, wherein the dry powder 30 is receivedinside the pressurized gas feeder 22. The dry powder inlet 211 of thegas-powder chamber 21 is detachably connected to the base 23 andcommunicated with the pressurized gas feeder 22.

Therefore, by compressing the pressurized gas feeder 22, the SAPHparticles of dry powder 30 is pressurized to enter the gas-powderchamber 21. When the air pump 22 is compressed, air is pumped in thegas-powder chamber 21 through a gas regulator 24, which is a one-way airvalve, and mixes with the dry powder 30 in the air-powder chamber 21.When the manual air pump 22 is released, additional air enters throughthe gas regulator 24 to prevent negative air pressure within gas-powderchamber 21 to ensure the mixture of dry powder and pressurized airpumping into the delivery channel 10 in a one-way manner without anyre-sucking back into the gas-powder chamber 21.

According to the preferred embodiment as shown in FIG. 1, the gasregulator 24 comprises a gas valve 240 provided at a side of thegas-powder chamber 21, which is about 2-5 cm preferably from the base 23and air communicating with delivery channel 10. A powder filter 241 isprovided between the gas-powder chamber 21 and the gas valve 240 toprevent any powder entering the gas valve 240.

The gas valve 240 according to the preferred embodiment as shown in FIG.1 comprises a hollow housing 242 having an air inletting opening 243, avalve ball 244 disposed inside the housing 242, and a position stopper245 provided at a bottom inside the housing 242. A diameter of the valveball 244 is smaller than the diameter of the housing 242 and larger thanthe inletting opening 243, and that the valve ball 244 can be movedbetween the inletting opening 243 and the position stopper 245. When thevalve ball 244 is pressed to block the inletting opening 243, the gasvalve 240 is closed from any air to enter. When the valve ball 244 isdropped to the position stopper 245, the inletting opening 243 is openedto enable air flowing into the powder supply device 20.

Accordingly, when the pressurized gas feeder (air pump) 22 iscompressed, a portion of the air pressure produced at the dry powderoutlet 212 (i.e. the position between the gas valve 240 and the feedingopening 11 of the delivery channel 10) presses the valve ball 244radically outwardly to block the inletting opening 243 so as to producethe air pressure in the gas-powder chamber 21 mixing with the dry powder30 and blow the dry powder 30 into the delivery channel 10 fordelivering the mixture of dry powder and pressurized air to the emittingopening 12 of the delivery channel 10 for spraying onto internaloperation site.

Once the air pressure is reduced when the compression to the pressurizedgas feeder 22 is released, the valve ball 244 drops and returns to theposition stopper 245 to reopen the inletting opening 243 so that air canenter the one-way gas valve 240 and supply to the pressurized gas feeder(air pump) 22 to release the negative air pressure therein in order toprevent any re-sucking of the dry powder 30 back to the pressurized gasfeeder 22.

Referring to FIG. 2, the gas regulator 24 comprises an alternative gasvalve 250 which comprises a housing 251 having an air inletting opening252, a resilient element 253 disposed within the housing 251, and ablocker 254 affixed to the resilient element 253 and positioned betweenthe inletting opening and the resilient element 253 within the housing251 for blocking or opening the inletting opening 252.

Accordingly, when the pressurized gas feeder (air pump) 22 iscompressed, a portion of the pressurized air produced at the dry powderoutlet 212 (i.e. the position between the gas regulator 24 and thefeeding opening 11 of the delivery channel 10) presses the blocker 254outwardly to block the inletting opening 252 so as to produce the airpressure in the gas-powder chamber 21 mixing with the dry powder 30 andblow the dry powder 30 into the delivery channel 10 for delivering themixture of dry powder and pressurized air to the emitting opening 12 ofthe delivery channel 10 for spraying onto internal operation site.

Once the air pressure is reduced when the compression to the pressurizedgas feeder 22 is released, the blocker 254 is rebound by the resilientelement 253 to return to its original position. When the pressurized gasfeeder (air pump) 22 is compressed, the ball 263 is pressed by the airpressure produced at the dry powder outlet 212 to move from the frontend piece 2611 towards the rear end piece 2612 to open the feeding valve260 for delivering the mixture of dry powder and pressurized air to theemitting opening 12 of the delivery channel 10 for spraying onto theinternal operation site.

Once the air pressure is reduced when the compression to the pressurizedgas feeder 22 is released, the ball 263 is rebounded by the springelement 262 to its original position to block the entrance of the frontend piece 2611 to close the feeding valve 260.

Referring to FIG. 3, the gas regulator 24 of the above preferredembodiment as illustrated in FIG. 2 further comprises a one-way feedingvalve 260 affixed at the dry powder outlet 212 of the gas-powder chamber21, positioning right after the gas valve 250. The one-way feeding valve26 comprises a seat 261 affixed inside the feeding opening 11 having afront end piece 2611 and a rear end piece 2622 defining a chambertherebetween, a spring element 262, and a ball 263 which is attached toa front end of the spring element 262 in such a manner that the ball 263is able to be moved axially inside the delivery channel 10 between thetwo end pieces 2611, 2612.

When the pressurized gas feeder (air pump) 22 is compressed, the airpressure produced at the dry powder outlet 212 presses the ball 263 tomove from the front end piece 2611 towards the rear end piece 2612 toopen the feeding valve 260 for delivering the mixture of dry powder andpressurized air to the emitting opening 12 of the delivery channel 10for spraying onto the internal operation site.

Also, once the air pressure is reduced when the compression to thepressurized gas feeder 22 is released, the ball 263 is rebound by thespring element 262 to its original position to block the entrance of thefront end piece 2611 to close the feeding valve 260.

Referring to FIG. 4, the gas regulator 24 of the above preferredembodiment as is substituted by an alternative gas regulator 24′ whichincludes an alternative gas valve 270 and an alternative feeding valve280 to substitute the gas valve 250 and feeding valve 260 respectively.The gas valve 270, which is provided at an air opening 210 formed at aside of the gas-powder chamber 21, comprises a resilient blockingelement 271 which is in umbrella shape and disposed in the gas-powderchamber 21 in a movable manner between a blocking position to block theair opening 210 when it is moved towards the air opening 210 and anopening position to unblock the air opening 210 when it is moved awayfrom the air opening 210. The feeding valve 280 is a one-way valve thatis normally closed and opens due to pressurized air pushing towards theemitting opening 12.

When the pressurized gas feeder (air pump) 22 is compressed, the airpressure produced at the dry powder outlet 212 presses the resilientblocking element 271 to block the air opening 210 and opens the feedingvalve 280 for delivering the mixture of dry powder and pressurized airto the emitting opening 12 of the delivery channel 10 for spraying ontothe internal operation site.

Once the air pressure is reduced when the compression to the pressurizedgas feeder 22 is released, the feeding valve 280 returns to its closeposition and the resilient blocking element 271 rebounds to its originalposition to reopen the air opening 210 so that air can enter the gasvalve 270 and supply to the pressurized gas feeder (air pump) 22 torelease the negative air pressure therein in order to prevent anyre-sucking of the dry powder 30 back to the pressurized gas feeder 22.

According to the preferred embodiment as shown in FIGS. 1 to 4, thepressurized gas feeder 22 is screwed to the base 23 which can beembodied as a hand piece base so that one can unscrew and detach thepressurized gas feeder 22 to refill powder 30 into the empty pressurizedgas feeder 22 or filling it with different powder medication. Also, itis appreciated that more than one pressurized gas feeders can be used toselectively communicate with the gas-powder chamber 21 for differentapplications.

Referring to FIG. 5, an alternative mode of the powder supply device 20′of the internal dry powder delivery system is illustrated, which isconnected to the feeding opening 11 of the delivery channel 10 similarto the above preferred embodiment as shown in FIGS. 1-4. The powdersupply device 20′ comprises a gas-powder chamber 21′ and a pressurizedgas feeder 22′.

The gas-powder chamber 21′ has dry powder inlet 211′ for feeding in apredetermined amount of dry powder therein and a dry powder outlet 212′communicating with the feeding opening 11 of the delivery channel 10.

The pressurized gas feeder 22′ produces pressurized gas in thegas-powder chamber 21′ mixing with the dry powder therein to form amixture of dry powder and pressurized gas for blowing into the deliverychannel 10 through the feeding opening 11 thereof. Thereby, a continuousfeeding of the pressurized gas and the mixture of dry powder andpressurized gas into the delivery channel 10 from the gas-powder chamber21′ substantially renders the mixture of dry powder and pressurized gasto deliver to the emitting opening 12 of the delivery channel 10 andspray onto the designated internal operation site.

The powder supply device 20′ further comprises a powder feeder 23′ whichis seadedly connected to the dry powder inlet 211′ provided at a side ofthe gas-powder chamber 21′ in a detachable manner while the exit opening231′ of the powder feeder 23′ is communicated with the dry powder inlet211′. The dry powder 30 is received in the powder feeder 23′ andarranged to feed into the gas-powder chamber 21′ through the exitopening 231′ and the dry powder inlet 211′.

The pressurized gas feeder 22′ which is a manual bladder air pumpsealedly connected to one end of the gas-powder chamber 21′ for pumpingpressurized air into the gas-powder chamber 21′ manually. The gasregulator 24′ comprises a one-way gas valve 221′ provided on thepressurized gas feeder 22′ and a feeding valve 280′ affixed at the drypowder outlet 212′ of the gas-powder chamber 21′, similar to that asshown in FIG. 4,

Accordingly, when the pressurized gas feeder 22′ is compressed, the gasvalve 221′ is closed to block any outside air entering the pressurizedgas feeder 22′ so as to pump in pressurized air into the gas-powderchamber 21′ mixing with the dry powder 30 therein, to open the feedingvalve 280′ and to blow the dry powder 30 into the delivery channel 10′for delivering the mixture of dry powder and pressurized air to theemitting opening 12 of the delivery channel 10 for spraying ontointernal operation site.

Once the air pressure is reduced when the compression to the pressurizedgas feeder 22′ is released, the feeding valve 280′ returns to its closeposition and the gas valve 221′ opens to enable external gas (outsideair) entering the pressurized gas feeder 22′ to release the negative airpressure therein in order to prevent any re-sucking of the dry powder 30back to the gas-powder chamber 21′ and the pressurized gas feeder 22′.

According to the preferred embodiment, the powder feeder 23′ is screwedto the dry powder inlet 211′ so that one can unscrew and detach thepowder feeder 23′ to refill the empty powder feeder 23′ or filling itwith different powder medication. Also, it is appreciated that more thanone powder feeders can be used to selectively communicate with the drypowder inlet 211′ for different applications.

FIG. 6 illustrates an alternative mode of the embodiment as shown inFIG. 5, wherein the powder feeder 23′ is substituted by a powered powderfeeder 23″ to automatically feeding in dry powder 30 into the gas-powderchamber 21′ and the pressurized gas feeder 22′ is also substituted by anelectrical pressurized gas feeder 22″ which is an electrical air pump toautomatically and continuously produce positive pressurized air into thegas-powder chamber 21′. Since both the powder feeder 23″ and thepressurized gas feeder 22″ are automate devices, processor can be usedto provide electronic control of the powder feeder 23″ to equipped withthe pressurized gas feeder 22″ to ensure continuous and smooth feedingof the mixture of dry powder and pressurized gas to the delivery channel10 and spraying onto the designated internal operation site.

It is worth mentioning that more than one powder feeders 23′ or 23″ canbe used to connect to the gas-powder chamber 21, 21′ which areselectively switched to equip with the pressurized gas feeder 22′, 22″to feeding dry powder through the delivery channel 10. Also, a cathetercan be used and functioned as the delivery channel 10.

Referring to FIG. 7, the internal dry powder delivery system of thepresent invention as embodied and disclosed in FIGS. 1 to 6 may furthercomprises an end cap 40 which is arranged to normally cover the emittingopening 12 and be removed to open the emitting opening 12 for sprayingthe dry powder 30 onto the internal operation site. According to thepreferred embodiment, the delivery channel 10 further comprises anadditional operation channel 13 along the length of the delivery channel10 and an operation cable 41 having one end connected to the end cap 40and another end extended through the operation channel 13 to connectwith a handle 411. The end cap 40 remains covering the emitting opening12 to prevent any body fluid such as blood, gastric juice, and etc.,entering the emitting opening 12 while inserting and extending thedelivery channel 10 inside the human or animal body to the designatedinternal operation (tissue/organ) site. When the emitting opening 12reaches a position adjacent to the designated internal operation site,the user can simply operate the handle 411 to pull the operation cable41 to pivotally move the end cap 40 away from the emitting opening 12 toopen it so as to enabling the mixture of dry powder and pressurized gasto be pumped to spray onto the designated internal operation(tissue/organ) site.

Alternatively, the end cap 40 can be detachably attached to the distalend of the delivery channel 10 to cover the emitting opening 12. Afterthe delivery channel 10 is inserted into the beings until the emittingopening 12 reaches a position adjacent to the internal operation siteand the mixture of dry powder and pressurized gas is deliver to theemitting opening 12, the pressure of the pressurized gas is capable ofpushing the end cap 40 to detach from distal end and open the emittingopening 12.

In view of above, the pressurized gas feeder of the present inventioncan selectively use one of following types of air pressure source:

1. By connecting to the manual air pump 22 as shown in FIGS. 1 to 5,physicians can either continuously or sporadically control the amount ofair/powder released into the gas-powder chamber 21, 21′. The gas valvesof the hand pump can prevent powder/air reflux, which ensure one-waydelivery to the designated internal operation site. Manual air pumpgives physicians simple control over the amount of powder and airentering the delivery channel 10.

2. Using the electrical pump as shown in FIG. 6 offers a more consistentflow of gas or air. The gas or air released from the electrical pumpwill enter the gas-powder chamber 21, 21′, mix with the dry powderparticles and go through the connected delivery channel 10. Gas valve isinstalled in the device to prevent air/powder reflux.

3. The device could be connected to medical-use oxygen, carbon dioxide,and other medical use clean-air to offer a continuously flow of gas andlimit the possibility of powder and tip occlusion in the deliverychannel 10. The gas supply to be used can be directly fed to theinletting opening 243 of the gas valve 240 as shown in FIG. 1, theinletting opening 252 of the gas valve 250 as shown in FIGS. 2 and 3,the air opening 210 as shown in FIG. 4, and the gas valve 221′ as shownin FIG. 5.

Referring to FIG. 8, an one way delivery system of hemostat powderduring surgery according to an alternative mode of the preferredembodiment of the present invention is illustrated, wherein theelongated tubular delivery channel 10 comprises a powder deliverycatheter 1 having a feeding opening at one end thereof and an emittingopening at a distal end thereof (i.e. the catheter tip), female luers 2and male luer locks 3 provided at the feeding opening of the powderdelivery catheter 1.

The powder supply device 20 comprises a gas powder mixer 4 providing agas powder mixing chamber and a powder dispenser (bellow) 5 which isscrewed to the gas powder mixer 4 and communicated with the gas powdermixing chamber therein. The hemostat powder is filled in the powderdispenser (bellow) 5 and is adapted to be delivered via the powderdelivery catheter 1 to the site of bleeding. The pressurized gas feeder22 of the powder supply device 20 further comprises a male luer lock 6,a gas delivery tube 7 having one end connected with the gas powder mixer4 and communicating with the gas powder mixing chamber therein via themale luer lock 6, a female luer 8 which is connected to another end ofthe gas delivery tube 7 and an external gas source 9.

During operation, the external gas source (pump) 9 is switched on firstto produce an airflow of 3 L/min, which is embodied as a ‘maintaininggas flow’. Insert the powder delivery catheter 1 through an endoscopeworking channel to a designated bleeding site. The maintaining gas flowis pumped through the gas delivery tube 7, the gas powder mixing chamber4 and the powder delivery catheter 1 to prevent reflux of gas and fluidinto the powder delivery catheter 1 from the gastrointestinal tractduring insertion of the powder delivery catheter 1 into the endoscope.Then, pump the powder dispenser 5 as a ‘working gas flow’ to deliver thepowder to the designated bleeding site through the powder deliverycatheter 1 to emit via the emitting opening thereof.

According to the alternative mode as shown in FIG. 8, to prevent frompowder occlusion in the powder delivery catheter 1 while inserting thepowder delivery catheter 1 into the endoscope working channel to itsdesignated position, a special feature of ‘dual gas channels’ isprovided. One of the gas channels provides the ‘maintaining gas flow’ toensure that the pressure inside the powder delivery catheter 1 is higherthan the pressure inside the gastrointestinal tract or thethoracic/abdominal cavity where the catheter tip is located. Thisprevents gas reflux from the gastrointestinal tract orthoracic/abdominal cavity into the powder delivery catheter 1 which mayresult in powder occlusion therein. The ‘working gas flow’ on the otherhand delivers the dry powder to the designated site through the powderdelivery catheter 1.

FIG. 9 illustrates an alternative advance mode of the powder deliverysystem as shown in FIG. 8, wherein the elongated tubular deliverychannel 10 also comprises a powder delivery catheter 1′ having a feedingopening at one end thereof and an emitting opening at a distal endthereof (i.e. the catheter tip), female luers 2′ and male luer locks 3′,wherein the female luers 2′ and the male luer locks 3′ are provided atthe feeding opening of the powder delivery catheter 1′.

The powder supply device 20 comprises a gas powder mixer 4′ providing agas powder mixing chamber 5′ therein and a powder dispenser 6′ which isscrewed on top of the gas powder mixer 4′ and filled with hemostatpowder 13′. The gas powder mixing chamber 5′ has an inlet end and anoutlet end connecting and communicating with the feeding opening of thepowder delivery catheter 1′ via a connecting channel 14′. The end wherethe connecting channel 14′ connecting the outlet end of the gas powdermixing chamber 5′ is defined as a connection point A. The powderdelivery catheter 1′ is inserted through the endoscope working channelto reach the bleeding site. The powder delivery system further comprisesa working gas flow switch 7′ and a maintaining gas flow switch 8′provided at the gas powder mixer 4′.

According to this alternative advance mode, the gas powder mixer 4′further comprises a hand piece 40′ integrally connected thereto, wherethe working gas flow switch 7′ and the maintaining gas flow switch 8′are installed to the hand piece 40′ for ease of operation. The handpiece 40′ has a working gas flow channel 9′ and a maintaining gas flowchannel 10′ extended therein, wherein one end of each of the working gasflow channel 9′ and the maintaining gas flow channel 10′ are joined forconnecting to an external gas source 12′ while another end of theworking gas flow channel 9′ is extended and connected to the inlet endof the gas powder mixing chamber 5′ and another end of the maintaininggas flow channel 10′ is extended and connected to the connecting channel14′ at a connection point B.

The external gas source 12′ supplies pressurized gas to flow through theworking gas flow channel 9′ as working gas flow to enter into the gaspowder mixing chamber 5′ and to flow through the maintaining gas flowchannel 10′ as maintaining gas flow to a position between the feedingopening of the powder delivery catheter 1′ and the outlet end of the gaspowder mixing chamber 5′. The working gas flow switch 7′ is provided ata positioned along the working gas flow channel 9′ for controlling thesupply of the gas flow therethrough and the maintaining gas flow switch8′ is provided at a position along the maintaining gas flow channel 10′for controlling the supply of gas flow therethrough.

During operation, the maintaining gas flow can be adjusted via themaintaining gas flow switch 8′ to a pressure higher than the pressure inthe gastrointestinal tract where the catheter tip is located. The powderdelivery catheter 1′ is inserted through the endoscope working channelto the designated bleeding site. The maintaining gas flow is pumpedthrough the maintaining gas flow channel 10′ all the way to the feedingend of the powder delivery catheter 1′ to prevent reflux of gas andpowder in the powder delivery catheter 1′ while the working gas flowremains closed at this point via the working gas flow switch 7′. Openthe working gas flow switch 7′ at the hand piece 40′. The working gasflow will enter the gas powder mixing chamber 5′ and push the powder inthe gas powder mixing chamber 5′ forward into the powder deliverycatheter 1′.

As shown in FIG. 9, the maintaining gas flow channel 10′ in the gaspowder mixer 4′ is separated from the gas powder mixing chamber 5′. Toensure the working mechanism of the dual gas channel configurationaccording to the present invention, the connection point B of themaintaining gas flow channel 10′ to the powder delivery catheter 1′ mustbe located closer to the male luer locks 3′ than the connection point Aof the gas powder mixing chamber 5′ with the powder delivery catheter 1′so as to allow the maintaining gas flow to bypass the gas powder mixingchamber 5′ while the working gas flow maintaining an unobstructeddelivery passage for the powder.

In view of above, besides the options for various air/gas sources, thepresent invention offers two types of air-powder chambers to provide atailor-made apparatus via endoscope for any minimally invasiveprocedures both for diagnosis and treatments.

The first option offers the three-way air-powder chamber with anexternal gas source, a powder feeder, a pressurized gas feeder, and adelivery channel (catheter) attached to the gas powder chamber. The mainbody of the gas powder chamber has two incoming openings, for both gasand the dry powder, and a dry powder outlet connected to the catheter.The incoming gas flow will mix with the dry powder released from thepowder feeder and then delivered through the catheter of the workingchannel via endoscope.

The second option provides a two-way air-powder chamber; it only has anincoming and outgoing opening. It differs with the previous device byeliminating the external powder feeder since the main mixing chamber ispre-filled with the dry powder. Once the gas is released, it mixes withthe dry powder and the mixture is delivered through catheter of theworking channel via endoscope. It is preferably for portable anddisposable usage due to its compact size and simplified structure.

The delivery channel 10 (powder delivery catheter 1, 1′) will preferablyused with medical-use materials such as PE and TEF. It is essential toselect a material that has the strength and the flexibility to beinserted into the working channel of endoscope and endure any folding ortwisting which could cause congestion. For gastro-intestinal endoscope,the diameter of the delivery channel 10 is preferably smaller than theregular working channel's diameter of the endoscope being used.Currently, the standard working channel diameters of gastro andintestinal endoscope are about 2.8 mm and 3.2 mm respectively. Thelength of the delivery channel 10 (powder delivery catheter 1, 1′)should be longer than the total length of the endoscope which it isinserted into. Normally, the average total length of gastro andintestinal endoscope are about 1600 mm and 2300 mm respectively.

Besides the incoming gas source and the outgoing channel, all connectingoutlets of the system should remain completely sealed throughout use tominimize air/powder reflux and tip occlusion.

It is worth mentioning that the pressure of gas should be maintainedhigher enough to overcome the resistance of particles with particles,particles with the systems, plus the pressure inside of gastro-intestinewhere the catheter tip located.

The internal dry powder delivery system of the present inventiondifferentiates itself from conventional medication delivery method inits specification for the delivery of dry powder particles via theworking channel of an endoscope. For example, prior art patent,WO2006/049463A1, focuses on liquid and gel-form medication delivery.Liquid's fluidity causes minimal obstruction in the working channel ofthe endoscope, which does not contain the same strategy and technologyas a dry powder delivery service via endoscope.

The current endoscope invention includes both gastro and intestinalendoscopes. It can be also adapted in laparoscope, thoracoscope,hysteroscope, cytoscope, laryngoscope, and nasopharyngoscope. Theworking channel diameter of laparoscope, thoracoscope, hysteroscope,cytoscope and laryngoscope are normally much bigger thangastro-intestinal endoscope. So the challenges will be less forphysicians to deliver the powder format drug to the wound sites vialaparscope, thoracoscope, hysteroscope, cytoscope and laryngoscope

The working channel mentioned above is the irrigation channel or abiopsy clamp channel in the endoscopic cannula.

The present invention offers a new powder format drug delivery methodfor physicians via endoscope. It could be used with various purposessuch as hemostatic, antibiotic, tissue repair, mucosal protection, ulcerrepair and antineoplastic treatment, etc.

The present invention offers a new technique for physicians to use anendoscope to access the abdominal cavity, thoracic cavity and pelviccavity via natural orifices to directly apply powdered medication to theinternal target tissue/organs for the purpose of hemostasis,anti-inflammatory, anti-adhesion, tissue repair, congenital defecttissue repair, fistula closure, topical and localizedchemotherapy/radiotherapy for tumor treatment, and etc. By using theinternal dry powder delivery system of the present invention, physicianscan directly apply the biocompatable polysaccharide hemostatic powder tothe bleeding sites via endoscope during invasive surgery to achievehemostasis.

When all components (pressurized gas feeder, gas-powder chamber, andworking delivery channel) are assembled, the present invention canprovide a complete and new applicator via endoscope. The manual air pumpand powder feeder allow physicians to control the flow of air and theamount of powder released through the delivery channel. The gas andfeeding valves provided to the gas-powder chamber will eliminateair/powder reflux. The mechanism of this system begins with the releaseof gas by a manual or electrical air pump, which mixes with the drypowder presented in the air-powder chamber. By compressing thepressurized gas feeder and/or the dry powder feeder, physicians caneasily control the amount of gas/powder mixture released into thedelivery channel. The gas flow continues to push the mixture throughoutthe entire delivery channel, overcoming any obstructions presented bythe channel wall and/or between particles.

By using the internal dry powder delivery system of as suggested in thepresent invention, physicians can directly apply the powder-formatbiocompatible adhesives to the wound site in the gastro-intestinal wallvia endoscope by minimal invasive surgery to achieve hemostasis andsealant treatment.

By using the internal dry powder delivery system as disclosed in thepresent invention, physicians can directly apply the antibiotic powderto the infection site in the gastro-intestinal wall via endoscope byminimal invasive surgery to achieve anti-infection treatment.

By using the internal dry powder delivery system as disclosed in thepresent invention, physicians can directly apply the anti-ulcer powderform medication to the ulcer site in the gastro-intestinal wall viaendoscope by minimal invasive surgery to achieve anti-ulcer treatment.

By using the internal dry powder delivery system as disclosed in thepresent invention, physicians can directly apply the anti-cancer/tumorpowder form medication to the cancer/tumor site in the gastro-intestinalwall via endoscope by minimal invasive surgery to achieve antineoplastictreatment.

By using the internal dry powder delivery system as disclosed in thepresent invention, physicians can directly apply the illustrating agentto the cancer/tumor site in the gastro-intestinal wall.

By using the internal dry powder delivery system as disclosed in thepresent invention, physicians can access internal organs in theabdominal, thoracic and pelvic cavities using an endoscope insertedthrough natural orifices to directly deliver medications to the targettissue/organ via the working channel of the endoscope for the purpose ofhemostasis, anti-inflammatory, anti-adhesion, tissue repair, congenitaldefect tissue repair, perforation repair, fistula closure, promote woundhealing, topical and localized chemotherapy/radiotherapy for tumortreatment etc. These dry powder materials include, but not limited to,biocompatible hemostats, adhesives, surgical sealants, anti-adhesionmaterials, tissue enforcement materials, fistula closure materials, wax,and etc.

By using the internal dry powder delivery system and method thereof asdisclosed in the present invention, physicians can applyanti-inflammatory medications, immunosuppressive medication, nutrientpowder (including trace elements, protein and amino acids), vaccines andother anti-microbial drugs directly into the digestive tract. Inparticular, it can be used in the treatment for chronic colitis,malnutrition, parasitic diseases, and etc.

The internal dry powder delivery system and method thereof as disclosedin the present invention can be specifically designed for examination,diagnosis and treatments practices in humans and mammals. It could alsobe used in forensic science such as autopsy, anatomy research andscientific experiments. Besides medical and scientific uses, theinternal dry powder delivery system of the present invention can beapplied in engineering, military affairs, navigation, and aviation.

The internal dry powder delivery system and method thereof as disclosedin the present invention can be specifically designed for examination,diagnosis and treatments practices in humans and mammals.

One skilled in the art will understand that the embodiment of thepresent invention as shown in the drawings and described above isexemplary only and not intended to be limiting.

It will thus be seen that the objects of the present invention have beenfully and effectively accomplished. It embodiments have been shown anddescribed for the purposes of illustrating the functional and structuralprinciples of the present invention and is subject to change withoutdeparture from such principles. Therefore, this invention includes allmodifications encompassed within the spirit and scope of the followingclaims.

What is claimed is:
 1. A method of delivering dry powder to an internaloperation site of beings, comprising the steps of: (a) extending adistal end of an elongated tubular delivery channel to a position thatan emitting opening of said delivery channel is adjacent to saidinternal operation site; (b) generating a working gas flow containingpressurized gas to mix with dry powder to deliver a mixture of drypowder and pressurized gas to said delivery channel until apredetermined amount of said mixture of dry powder and pressurized gassprays out from said emitting opening of said delivery channel forapplication onto said internal operation site; (c) generating amaintaining gas flow to said delivery channel for preventing gas refluxof said delivery channel so as to prevent reflux of gas and fluid intosaid delivery channel, wherein said pressurized gas is mixed with saiddry powder in a gas powder chamber to deliver said mixture of dry powderand pressurized gas from said gas powder chamber into said deliverychannel, wherein an outlet of said gas powder chamber is communicativelylinked to said delivery channel; and (d) bypassing said maintaining gasflow to said gas powder chamber, such that said maintaining gas flowdoes not pass through said gas powder chamber.
 2. The method, as recitedin claim 1, further comprising the steps of: (e) configuring a workinggas flow channel to communicate with an inlet of said gas powder chamberto guide said working gas flow thereinto; and (f) configuring amaintaining gas flow channel to communicate with a connecting channel,which connects and communicates said outlet of said gas powder chamberwith said delivery channel, to guide said maintaining gas flow to saiddelivery channel.
 3. The method, as recited in claim 2, wherein saidworking gas flow channel and said maintaining gas flow channel areconnected to a single gas supplying source.
 4. The method, as recited inclaim 2, wherein the step (c) further comprises the steps of controllinga supply of said working gas flow to said gas powder chamber via aworking gas flow switch, and controlling a supply of said maintaininggas flow to said delivery channel via a maintaining gas flow switch. 5.The method, as recited in claim 1, wherein the step (c) furthercomprises the steps of controlling a supply of said working gas flow tosaid gas powder chamber via a working gas flow switch, and controlling asupply of said maintaining gas flow to said delivery channel via amaintaining gas flow switch.
 6. The method, as recited in claim 5,wherein said working gas flow switch is connected at said working gasflow channel and said maintaining gas flow switch is connected at saidmaintaining gas flow channel.
 7. The method, as recited in claim 1,wherein said maintaining gas flow is generated to reach said internaloperation site before said working gas flow is generated to deliver saidmixture of dry powder and pressurized gas at said internal operationsite.
 8. A method of delivering dry powder to an internal operation siteof beings, comprising the steps of: (a) extending a distal end of anelongated tubular delivery channel to a position such that an emittingopening of said delivery channel is adjacent to said internal operationsite; (b) generating a flow of pressurized gas and dividing saidpressurized gas into a working gas flow and a maintaining flow, theworking gas flow provided to mix with dry powder in a gas powder chamberto deliver a mixture of dry powder and pressurized gas to said deliverychannel until a predetermined amount of said mixture of dry powder andpressurized gas sprays out from said emitting opening of said deliverychannel for application onto said internal operation site, wherein saidworking gas flow and said maintaining gas flow are generated from asingle gas supplying source; (c) preventing reflux of gas and fluid intosaid delivery channel by said maintaining gas flow generated to saiddelivery channel; and (d) bypassing said maintaining gas flow to saidgas powder chamber, such that said maintaining gas flow does not passthrough said gas powder chamber.
 9. The method, as recited in claim 8,further comprising the steps of: (e) configuring a working gas flowchannel to communicate with an inlet of said gas powder chamber to guidesaid working gas flow thereinto; and (f) configuring a maintaining gasflow channel to communicate with a connecting channel, which connectsand communicates said outlet of said gas powder chamber with saiddelivery channel, to guide said maintaining gas flow to said deliverychannel.
 10. The method, as recited in claim 9, wherein said working gasflow channel and said maintaining gas flow channel are connected to saidsingle gas supplying source.